Classic Turbos

Classic Turbos

A SPIN BACK IN TIME

Whilst turbochargers were fitted to one or two trucks before WW2 and the P38 fighter during it, the first production car was the 1961 Chevrolet Corvair, a car Ralph Nader would later have you believe was "unsafe at any speed" but in the meantime someone at GM thought "Hey, lets give it more power, with turbo lag, that will really hot things up".  A few weeks later the Oldsmobile Jetfire also recieved a Turbo option. The company was trying to boost the performance of its little 215cu in all alloy V8 which was a bit wimpy hauling a large gathering of Detroit steel around. The engine was high compression (over 10:1!) and used a water/alcohol mix injected into the intake to prevent detonation. Owners didn't like the inconvenience of buying and topping up the special 'Turbo Rocket Fluid' and after many mechanical failures, they were withdrawn just a year later. Ironically, the rights to the normally aspirated version were then sold to Rover, where it became the UK 'muscle' engine of choice, later transplanted into just about everything on 4 wheels (and 3, there is a trike near me sporting one!)

Things went quiet until BMW went all adolescent in 1973 with the 2002 Turbo. The launch models carried large stripes down the side in the colours of Texaco, BMW's racing sponsors (which subsequently became embedded as the Motorsport division colours) and the word 'TURBO' on the front spoiler, reversed so it was the right way around in your rear view mirror to suggest you get out of the damn way. The press thought this was most inappropriate for understated German style (the Mullet was yet to take hold) and BMW backed down, just putting the decals on the option list. The turbo lag was by all accounts monumental and a sudden onset of boost into 185mm wide tyres halfway around a bend in a rear wheel drive car sent many on a ditch hunt. Learn it, tame it though, and you had one of the fastest cars across country of its day, which gave Porsche a scare. Launched into the 1973 fuel crisis, it became socially unacceptable to not just run a thirsty car, but to boast about it with big stripes so less than 1700 were made.

Porsche had taken note and in 1975 launched the 911 Turbo (actually it considered the model so different it tried to market it as the 930 Turbo in North America) and things got really rapid and a legend was born. 300 bhp in the light 911 was big power to weight back in the 1970's. Since then, when you look at the hard figures, nothing much touches the top of the 911 pack as an everyday motor.

But it was Saab who endowed the common man with  the power of 'TURBO'. Its 99 model, with its neat badge where the 'O' of Turbo was in the shape of the turbocharger vanes, became an instant marketing machine. Yet it wasn't badge engineering, the 99 Turbo took the fight to the hot hatchbacks that were popping up and beat them and traditional sports cars like the TR7 were dead in the water by comparison. In the most useful part of a cars performance that nobody ever measures, overtaking, it could trounce some pretty exotic machinery. Stig Blomqvist and Per Eklund are the legends that took the Saab Turbo rallying in 1978. At the Swedish event in 1979 it became the first turbocharged car to win an International Rally.

If you experienced the 1980's you'll remember the marketing buzzword was 'TURBO'. Any car with that badge on the rump was to be respected and it wasn't long before vacuum cleaners were called "Turbo' and there was even a cologne for men called 'Turbo' that apparently made you irresistable to women... although if you smelt it I'm sure most ladies would disagree. The word was unstoppable.

I was lucky enough in a former life in marketing to do the Advertising for Geoff Kershaw at Turbo Technics. Whilst he was at Garratt AiResearch, he had developed the Turbo installation with Saab and later went on to offer Turbo conversions for many road cars. I test drove many of them on the way to photoshoots and can attest their performance. Geoff went on to invent a machine that balances turbochargers after rebuilds and selling them to just about every turbo repair shop. I was shown the prototype in a corner of the workshop and barely acknowledged it, the road car tuning was exciting, but a steel box was not. I bet Geoff made more money from those balancing machines than anything else. If you ever want to see real performance figures, look up his 'Minker' project.

CLASSIC TURBO CARE

So, many classic cars now sport a turbo and in the future so will many more. They have become not just a method of performance, but one of economy too. Use a smaller capacity engine than you would normally put in a car and add a turbo for the times when some grunt is needed. Whilst it is off boost the vehicle will be more economical than a bigger engine that's under-utilised. Today many owners wouldn't even know they have a turbocharger under the bonnet, there won't even be a badge to give them a clue.

Is there anything to know about these older Turbos? Well, that clever bit about them, that they use the otherwise wasted exhaust gases from the engine to pwer them, means they get very hot. This can mean hot enough on some installations to glow red after a long hard run(!) They also spin at very high rpm, many times that of the engine so the bearing that holds the turbine shaft is under a lot of pressure, both in absorbed heat and high speed. In modern Turbos this bearing is water cooled which helps keep it on the straight and narrow. Sometimes its a ball or roller bearing, but usually in earlier incarnations its a plain bearing where the oil itself provides the thin film which allows the turbine to spin with low friction. Nothing wrong with that, simple and works well, provided you treat it right. Things to consider:

1) After a long run slow for the last half mile letting the Turbo cool down from the fresh oil feed, then let it idle for a while before switching off. If you don't, the oil can bake in the turbo and you can imagine what that does eventually. Just about everyone knows this trick when they get home, but have you thought about that fuel or rest stop? Straight up to the pump and switch off I bet?

2) Don't blip the throttle before switch off, the turbine speeds up with the blast of exhaust gases and is still freewheeling after you turn off the ignition but the oil pump is no longer pushing oil into that vital bearing.

3) Regular oil changes are crucial as the oil comes under vastly more pressure than a non-turbo engine and modern synthetics, if suitable for your engine, handle these temperatures far better.

4) Sludge build up in the sump is a killer as it can block the arteries to the turbo, the oil feed and drain pipes. This can be from cooked oil, carbon build up and lack of maintenance. The cylinder pressures of a Turbo engine often means more 'blow by' past the piston rings which contaminates the oil faster. Interestingly, if you are buying a turbocharged petrol Saab 9-5 experts generally recommend the highest performance 'HOT' versions as these had synthetic oil as standard in the service regime and suffer less sludge issues than the more sensibly driven. lower performance 'standard oil' versions.

5) Earlier engines do not have Intercoolers so be careful on high temperature days and/or higher altitudes as there is a possibility that detonation or 'knock' can set in if the engine is not tuned to suit. Not too much of a risk in the UK but you never know that heat wave might happen one day!

IF IT BLOWS, IT SUCKS

If the Turbo gives up you'll soon know, the bearing failure leads to seal failure and then the stream of oil into the exhaust will have you replicating one of the Red Arrows as you traverse to the hard shoulder. Stop as soon as safely possible as with bearing failure the turbines will strike the housing and bits of titanium turbine in your combustion chambers will make an already bad day, much worse.

Replacement cartridges which comprise the turbines and bearing, onto which you fit your existing housings and wastegate, are relatively cheap in comparison to not so long ago when you had to buy a whole turbocharger. These are known as CHRA's or 'Centre Housing Rotating Assembly'. Its not a mystery to fit them, take lots of pics of the original unit to make sure you get all the orientations correct. Lubricate the bearing on assembly and prime the system before start up. Some cartridges come with a syringe to ease the former.

A very thorough clean of the whole pipework system is then required, especially the intercooler if one is fitted, you never know what bits are in there and you don't want them entering your engine after you've done all this work.

Also watch out if you have a head gasket failure. When the oil and water of an engine have mixed and made that lovelly mayonaise which is fun to remove, you can almost guarantee the turbo bearing will be knocked out too. So its head gasket and a turbo just to be doubly painful. Just proves preventative maintenance goes a long way.

After any failure, clean out or replace the turbo oil feed and drain pipes otherwise you'll be pumping old oil/water creamy froth or sludge into your sparkling new turbo. If you can drop the sump for a clean out thats a great preventative measure too.

I'm off to do some gardening with my trusty Turbo Rake.

 

Tags: Turbo


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